While assembled electronic circuitry has been dramatically reduced in size, the use of soldering as a method for forming both an electrical and fixable attachment of electronic components to a substrate has remained quite prevalent. However, such attachments require that the variety of components be held in desired positions prior to completing the aforementioned solder attachments, and post electrical underfill connection. An underfill connection can increase the thermal fatigue life of a solder ball connection, environmentally protect the connection, and provide greater mechanical shock and robustness to the assembled electronic circuitry.
A number of solutions for temporarily holding components in such desired positions have been developed and used with some success. For example, a tack agent can be used to secure such components to the substrate while solder bond or solder ball connections are made through the application of heat. After such temporary connections are made, the tack agent can remain as a contaminant or the assembly subjected to an extra processing step designed to remove such contamination. For some of the aforementioned solutions, a fluxing agent is provided separately from the tack agent, for example by applying such fluxing agent in a distinct application step, separate from the application of the tack agent. In other solutions the fluxing agent is provided in a combination with the tack agent, for example where a solder paste is used as the tack agent and fluxing agent is either added thereto or prereacted therewith.
In still other solutions, (see, U.S. Pat. No. 5,177,134 or US Published Application No. 2009/0294515, the '134 patent and the '515 application, respectively) a tack agent and fluxing agent are admixed where upon soldering, the tack agent either volatilizes or decomposes. However it has been found that where the tack agent is either volatized or decomposed at or above solder reflow temperatures, as each of the above teaches, either solder reflow is limited, significant contamination from the tack agent can remain or specialized process equipment is required.
Therefore new solutions that can provide a single material that holds components in desired positions prior to completing solder attachments (i.e., performs as a tack agent), provide for any fluxing that might be desired (i.e., performs as a fluxing agent) and also provides a post electrical connection underfill would be desirable. Further it would be advantageous if such solutions would eliminate the need for specialized equipment, as described above, and reduce or eliminate the problems with achieving desirable solder reflow and/or associated with any contamination that might result therefrom.